How to pass color value from input to output in custom python node
From the code above I'm not exactly sure how to give a contextually direct solution, but in an attempt to help move along the issue...


Set up a node tree reference: 

tree = bpy.context.scene.node_tree
Set up a link reference:

your_links = tree.links
Make your links:

your_link = your_links.new(your_node.outputs[0],another_node.inputs[0])


To change the values you could do something like:

your_node.inputs[0].default_value = 0.3